Photographic layers which contain uvabsorbers

ABSTRACT

The light stability of color photographic images is improved by overcoating the image carrying layer with a UV-protective coating which contains a UV-absorbing compound. The UV-absorbing layer contains as UV-absorbent a 2-phenolbenzotriazole, the benzo ring of which is substituted with at least 1 alkoxy group.

e i l: u W Elite Saies aiei [1 1 [111 3,754,919 Sobel et al. I Aug. 28, 1973 PHOTOGRAPHIC LAYERS WHICH CONTAIN UV-ABSORBERS [56] References Cited [75] Inventors: Johannes Sobel; Fritz Nlttel; v UNITED STATES PATENTS Wolfgang Himmelmann; Willibald 3,253,921 5/1966 Sawdy 96/73 Pelz, all of Qplad G r 3,004,896 10/196l Heller et al. 252/300 [73] Assignees Agia-Gevaert Aktiengesellschaft, FOREIGN PATENTS OR APPLICATIONS Leverkusen, Germany 879,144 Great Britain 96/84 [22] Filed: 1971 Primary Examiner-Ronald H. Smith [21] App]. No.: 210,611 Attorney-Connolly & Hutz Related US. Application Data [57] ABSTRACT [63] Continuation of Ser. No. 878,220, Nov. 19, 1969,

The light stability of color photographic images is improved by overcoating the image carrying layer with a UV-protective coating which contains a UV-absorbing abandoned.

[30] Foreign Application Priority Data I D 6 1968 G P18131618 compound ec. ermany The UV-absorbing layer contains as UV-absorbent a [52] US Cl 96/84 R 96/74 252/300 -phenolbenzo-triazole, the benzo ring of which is [51] hit Cl .IIIIIIIIIIIIIIIIIII dose 1/84 substituted with at least 1 alkoxy p.

[58] Field of Search 96/84 UV; 252/300 2 Claims', No Drawings PHOTOGRAPHIC LAYERS WHICH CONTAIN UV-ABSORBERS This is a continuation of application Ser. No. 878,220, filed Nov. 19, 1969, and now abandoned.

The invention relates to photographic layers which contain UV-absorbent compounds.

Numerous compounds are known which absorb light in the UV-region of the spectrum and are, therefore, suitable for the production of UV-filters and UV- protective coatings. Such coatings are used in photographic material for increasing the light fastness of colour images. The UV-absorbent compounds should be incorporated in a separate protective layer in as high a concentration as possible in order to achieve the great est possible effect. Generally, it is not possible to use the UV-absorbent compounds homogeneously or heterogeneously distributed with the image dyes in one layer, because the absorbent compounds and the dyes are very frequently found to interact with each other so that bleaching of the image is increased. The UV- absorbent compounds should be colourless and should have a high coefficient of extinction in the UV-region and should be as stable as possible.

The UVabsorbent compounds can be used in many different ways, e.g. in water insoluble binders. In this case, the finished colour image is coated with such a solution in a separate working step. This procedure, however, is only economical for images of large shapes and sizes and is, therefore, not generally applicable. Incorporation of water soluble and water insoluble UV- absorbent compounds in a diffusion fast manner in a protective layer has also been described. In this case, the chemical and physical properties of the UV- absorbent compound must meet certain requirements, e.g. it must be possible for the absorbent compound to be used in a highly concentrated form in layers of a thickness of l to 2 pm without precipitating from the protective layer in the form of crystals or an oil. The UV absorbent compound must, of course, be inert towards photographic processing baths and must not undergo yellowing on exposure to light.

A very wide variety of UV-absorbent compounds have already been described for the present purpose. None of these compounds, however, sufiiciently satisfies the requirements in practice. Aromatic azines have, inter alia, been particularly recommended as UV- absorbent compounds, but these generally have a high melting point so that they are difiicult to use because of their tendency to crystallise. Derivatives of this type which can easily be incorporated in photographic layers, which are described in German Patent No, 1,182,066, are slightly yellowish so that they are detrimental the white color images. The reason for this is that a slight absorption of light from the visible region of the spectrum occurs.

It is among the objects of the present invention to produce photograhic layers which contain UV absorbers, which must be easily incorporated in these layers, and as far as possible, must absorb only in the UV-region of the spectrum.

We now have found that compounds of the following formula are excellently suitable as UV-absorbers in photographic materials v II in which R and R are hydrogen, alkyl or alkoxy groups with up to l8 C-atoms, preferably with up to four C-atoms, in particular branched alkyl or alkoxy groups, but at least one of the substituents R and R is an alkoxy group; R stands for hydrogen or alkyl with up to five carbon atoms in particular methyl. Particular utility is exhibited by the following compounds:

Compounds to be used according to the invention are prepared in known manner. With compound 1, for example, 4-nitro-l,2-diisopropoxybenzene may be used, which can be obtained in known manner from l,2-diisopropoxy-benzene by nitration. The nitro compound is hydrogenated over Raney nickel and is then added in known manner to diazotised o-aminophenol. 4,5-dially advantageous absorption properties are unexpected. The absorption curve drops steeply towards the longwave region and is shifted by about nm towards the shorter wavelengths compared e.g. with 2-ohydroxyphenyl-benzotriazole UV-absorbent compounds which only contain alkyl groups as the substitucuts.

The UV-absorbent compounds are particularly readily soluble in those particular solvents which are used as so-called oil forming agents in the production of photographic materials. The solution can easily be emulsified in the casting solutions for the layers.

The UV-absorbent compounds to be used according to the invention may also be used in combination with other UV-absorbent compounds particularly with those of the 2-hydroxyphenyl-benzotriazole series.

The UV-absorbent compounds do not deleteriously influence the photographic properties of adjacent layers and in particular the color coupling reaction of dissolved dye derivatives is not reduced. Many of the known UV-absorbent compounds even of the benztriazole series are detrimental in this respect. The molar extinction coefficient is exceptionally high, so that the quantity of UV-absorbent compound used can be kept compartively low.

The UV-absorbent compounds are preferably emulsified in the casting solutions for the particular layer in the form of their solutions in high boiling solvents, by using a suitable dispersing apparatus.

The proportions in which the UV-absorbent compounds are mixed with the solvents may vary between 1:1 and 1:0.1. Low boiling auxiliary solvents such as ethyl acetate, methylene chloride, alcohols and mixtures of these solvents may be used. After dispersion, the low boiling solvents are removed in thin layer evaporators under vacuum. Suitable water insoluble, high boiling compounds are, for example, dibutyl phthalate. tricresyl phosphate and particularly higher fatty acids, and preferably branched fatty acids having about 10 to 20 C-atoms.

The UV-absorbent compounds may be added directly to the silver halide emulsions which contain color couplers or to a gelatin-containing solution of the protective layer.

The gelatin layers which contain the UV-absorbent compound may be arranged in any position in the various layers of the photographic material, but are preferably positioned above the layers which contain the image dye.

The UV-absorbent compounds are particularly suitable as the topmost layer for photographic multilayered materials of the usual arrangement.

The concentration of the UV-absorbent compounds in the layers may vary within wide limits. An addition of 10 to 50 percent by weight, based on the binder in the layer, has proved to be sufficient.

When using multi-layered color photographic materials, the concentration is so chosen that on exposure to The improvement in fastness is determined by exposing both images at the same color density to the same degree of bleaching. The ratio of lux hours required gives a measure of the improvement factor. The improvement factor depends not only on the concentration of the UV-absorbent compound but also on the thickness of the protective layer.

The layers which contain the UV-absorbent compound are completely transparent in the dry state and 10 practically color-less. They are stable against the photographic processing baths, e.g. a colorforming development bath. No yellowing can be detected after prolonged exposure to light.

EXAMPLE 1 A solution of 30 g of compound I, 3 g of bis-(2- ethyl)-hexyl-sulfosuccinate and g of a mixture of highly branched aliphatic carboxylic acids having 15 to 19 C-atoms and 30 g of ethanol and 30 g of methylene 20 chloride are emulsified at 50C with 1 liter of a 10 percent gelatin solution which contains 50 ml of a 10 percent saponin solution as wetting agent.

A mixing siren is used as the emulsifying apparatus. The dissolved UV-absorbent compound is introduced 5 near to the motor of the mixing siren through a tube.

After the addition of the UV-absorbent compound, stirring is continued for another 15 minutes.

The above mixture is applied onto a processed multilayer colorphotographic material bearing a color-image in true colors (layer thickness 3 #m).

The light fastness of the color photographic images is greater by a factor of 10 than that found when testing the protective layer which contains no UV-absorbent compound.

EXAMPLE 2 A casting solution for a layer containing UV- absorbent compound is prepared as follows:

A solution of 30 g of compound 6, 3 g of (2-ethyl)- hexyl-ester of sulfosuccinic acid and 15 g of a branched light the stability of the image dyes is equally satisfac- 0 aliphatic carboxylic acid having 15 to 19 C-atoms in g of dimethyl-formamide and 15 g of methylene chloride is emulsified at 50C. with 1 liter of a 10 percent gelatin solution which contains 50 ml of a 10 percent saponin solution as wetting agent.

A commercial multi-layered color photographic material is coated with the above casting solution as described in Example 1. The light fastness of the finished image is greater by a factor of about 10 than that of an untreated photographic material.

EXAMPLE 3 The same procedure is used as described in Example 1 but in the casting solution for the layer which contains the UV-absorbent compound, the mixture of branched fatty acids is replaced by an equal quantity of dibutyl phthalate.

Equally good results are obtained from this procedure after suitable processing.

EXAMPLE 4 The exceptionally high compatability. with conventional binding agents for photographic UV-absorbing layers in the presence of oil formers in opposition to chemically similar known compounds such as described in U.S. Pat. No. 3,253,921 is shown in the following example:

Test l: Into 1 liter ofa 10 percent aqueous gelatin so- 3 ,754,9 1 9 6 lution which contains 2 ml of a 50 percent aqueous cessed multilayer color photographic material in the solution of phenol is emulsified at a temperature of manner described in Example 1. Compounds of the in- 55C during a time of 5 minutes, a solution of 100 vention do not crystallize in the layer. The protective g of a compound 7, 5 g of the bis-(2-ethyl)-hexyl action of the UV-absorbing layers containing comester of sulfosuccinic acid in 200 g of ethyl acetate. 5 pounds of the present invention is considerably higher After emulsification it is stirred for 5 minutes and the than the protective action of layers containing the ethyl acetate evaporized. above prior art compound,

an 7. new w, v, Tfi3LgE After Storage at 40 C. Storage in the refrigerator at 5 C. After evaporation of Test emulsifying the solvent 4 hours hours 2 days 5 days 2 days 5 days 1 No No No No N0 Beginning No No.

precipitation. 2 a. No No No N0 No No No No. 3 Beginning Beginning Advancing Strong pre- Strong pre- Strong pre- Beginning Advancing precipitation. precipitation. precipitation. cipitation. cipitation. cipitation. precipitation. precipitation. 4 No No Beginning Beglnning... Advancing Strong Beginning Advancing.

Test 2: The test is performed in the same manner What is claimed is:

with the exception that the ethyl acetate solution 1- A photographic material comprising at least one contained ddi i ll 100 g f tri l h hate, layer containing a silver halide emulsion and incorpo- Test 3: The test is performed in the same manner as rated in a layer of said photographic material a UV- test I with the exception that the ethyl acetate soluabsorbing compound of the following formula:

tion contained 400 g of the solvent and with 2-(2'-hydroxy-3', H

5'-di-tert.-amylphenyl)-benzotriazol instead of compound 7. l jfi Test 4: The test is performed in the same manner as test 2 with the exception that the ethyl acetate solution contained 400 g of the solvent and with the comparison compound of test 3 instead of compound 7. in which The above samples were stored at 40C and in the re- R, and R are, independently of each other, branched frigerator and the behaviour of the emulsions with repropoxy or butoxy groups; spect to the precipitation of the UV-absorbing agents R is hydrogen or an alkyl group having up to five C- is observed Results are shown in the following table. atoms.

It is readily apparent from the above results that the 2. The photographic material of claim 1, wherein the casting solutions of the compounds used in accordance UVabsorbent compound is contained in said layer in with the invention are far more stable, therefore far an emulsified form as a solution in a high boiling solbetter to handle than the prior art compounds. vent.

The above samples were also applied onto a pro- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,791,919 Dated Aug. 28. m7?

Inventor) Johannes Sobel et al It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Front page, the heading [75] should read as follows:

-- Inventors: Johannes Sobel, Leverkusen, Germany; Fritz Nittel, Koeln 80, Germany; Wolfgang Himmelmann, Koeln 80, Germany; Willibald Pelz, Opladen, Germany.

Signed and sealed this 30th day of April 197a.

(SEAL) Attest: v v

EDWARD I LFLETCHERJR. G. MARSHALL DANN I Attesting Officer Commissioner of- Patents 505M PC4050 (10- 9) USCQMM-DC 60376-P89 f U.S. GOVERNMENT PRINTING OfflCE "l9 0-305-835,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,754,919 Dated Aug. 28. ILQ'T? Inventor) Johannes Sobel et all It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Front page, the heading [75] should read as follows:

-- Inventors Johannes Sobel, Leverkusen, Germany; Fritz Nittel, Koeln 80, Germany; Wolfgang Himmelmann, Koeln 80, Germany; Willibald Pelz, Opladen, Germany.

Signed. and sealed this 30th day of April 1971;.

(SEAL) Attest:

EDWARD MEEETCHERJR. G. MARSHALL DANN Attesting Officer Commissioner of,Patents F RM FO-1050 (10-69) USCOMM-DC 60376-P69 w U.S. GOVERNMENT PRI NIING OPTICS: "Cl 0-.Nl-J3l, 

2. The photographic material of claim 1, wherein the UV-absorbent compound is contained in said layer in an emulsified form as a solution in a high boiling solvent. 